1. Field of the Invention
Embodiments of the present invention relates to integrated circuit semiconductor devices and/or methods of fabricating integrated circuit semiconductor devices.
2. Description of the Related Art
As technology progresses, integrated circuit semiconductor devices formed on semiconductor wafers are decreasing in size and require more functionality to perform applications. For example, an integrated circuit semiconductor device, which uses an external power source to improve clock speed, may require a large driving current. In an integrated circuit semiconductor device used in a mobile device, even if the clock speed is low, low power dissipation may be required. A high-speed integrated circuit semiconductor device and a low-power dissipation integrated circuit semiconductor device have different threshold voltages. These threshold voltages affect the driving current of a transistor.
Integrated circuit semiconductor devices included on a semiconductor wafer may have different threshold voltages due to manufacturing variations. For a high-speed integrated circuit semiconductor device, the concentration of impurity ions for controlling the threshold voltage may be low. The high-speed integrated circuit semiconductor device may therefore be sensitive to variations in threshold voltages. For example, the variations in threshold voltages in the respective regions of the semiconductor wafer may reduce manufacturing yield and degrade reliability of manufactured integrated circuit semiconductor devices.